As electronic components and electronic systems have become more complex, the design of these components and systems has become a more time consuming and demanding task. Software simulation of electronic components and systems has become an important tool for designers. Simulation of a design is the execution of an algorithm that models the behavior of the actual design. Simulation provides the ability to analyze and verify a design without actually constructing the design and has many benefits in the design process. However, rigorous simulation can lead to undesirably long simulation run times.
Flash memory is being incorporated into a wide range of applications such as computer BIOS (Basic Input/Output System) chips, electronic film for digital cameras, memory cards for video game systems, and memory in wireless communications devices. Flash memory cells are generally floating-gate transistors. The data value of such cells is determined by the amount of charge stored on its floating gate. Programming and erasing flash memory cells is generally accomplished using voltages having a higher magnitude than a supply potential. These voltages are often generated internally to the flash memory device using charge pumps. Although charge pumps are complicated to model, charge pumps are popular because of their consumption of little power when in shutdown mode and their relatively small layout requirement.
Charge pump models are used to aid the design of memory devices or other integrated circuits utilizing charge pumps. Conventional charge pump models used in the simulation are limited by the speed of the simulation and limited by complex or inaccurate model representations. To simplify simulation, common resistive load voltage sources may be used to emulate actual charge pump behavior, but this does not address the non-linearity of an actual charge pump in which the output current diminishes with increasing magnitude of its voltage output.
Sophistication in the charge pump model is a cause of delay in design simulation. When the simulation is run, rigorous charge pump models can contribute to long analog simulation times. Therefore, for the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for alternative methods of modeling charge pump behavior in the design of integrated circuit devices.